Pulse discrimination device and electrocardiogram analyzer

ABSTRACT

A pulse discrimination device is configured to receive electrical signals from a plurality of positions of a living body to which a pacing device for outputting a pacing pulse to cause a heart to beat is attached, and is configured to discriminate the pacing pulse included in the electrical signals. The pulse discrimination device includes: a differential processor configured to calculate a difference of the electrical signals received from the plurality of positions; a sum processor configured to calculate a sum of the electrical signals received from the plurality of positions; and a pulse discrimination unit configured to discriminate the pacing pulse included in the electrical signals based on the difference obtained by the differential processor and the sum obtained by the sum processor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a division of U.S. patent application Ser. No. 16/573,002 filedSep. 17, 2019, which claims the benefit of Japanese Patent ApplicationNo. 2018-179345 filed on Sep. 25, 2018, the contents of which areincorporated herein by reference.

TECHNICAL FIELD

The presently disclosed subject matter relates to a pulse discriminationdevice and an electrocardiogram analyzer, and particularly to a pulsediscrimination device and an electrocardiogram analyzer that receive anelectrical signal from a living body to which a pacing device isattached so as to discriminate a pacing pulse included in the electricalsignal.

BACKGROUND

In related art, there has been proposed a pulse discrimination devicethat discriminates a pacing pulse that is output from a pacing devicesuch as a pacemaker in order to cause a heart to beat. The pulsediscrimination device receives an electrical signal from a living bodyto which a pacing device is attached and discriminates a pacing pulseincluded in the electrical signal. For example, a pulse discriminationdevice is built in an electrocardiogram analyzer such as a patientmonitor and an electrocardiograph, generates an electrocardiogram basedon an electrical signal received from a living body, and discriminates apacing pulse included in the electrical signal. Thus, for example, theoutput timing of the pacing pulse can be displayed on theelectrocardiogram, and the electrocardiogram can be analyzed in detail.

Here, the electrical signal from the living body is received via anelectrode portion disposed on the living body. However, the pacing pulsemay not be reliably detected depending on a position of the electrodeportion with respect to the pacing device.

As a technique for reliably detecting a pacing pulse, for example,JP-A-2009-240623 proposes a pacemaker pulse detection device thatimproves the detection accuracy of a pacing pulse without increasing thenumber of electrode portions to be used. The pacemaker pulse detectiondevice detects an electrical signal from a plurality of directions withrespect to a pacemaker using three electrode portions, and thus iscapable of obtaining an electrical signal having a potential differencefrom any one of the electrode portions, and it is possible to reliablydetect a pacing pulse.

However, the electrical signal received from the living body may includea noise similar to the pacing pulse, and the pacemaker pulse detectiondevice of JP-A-2009-240623 cannot discriminate between a pace pulse anda noise with high accuracy, and thus may detect the noise included inthe electrical signal as a pacing pulse.

For example, if a pacing pulse and a noise are discriminated based onlyon the amplitude of the electrical signal, the noise may be erroneouslydetected as the pacing pulse, and it is difficult to discriminate thepacing pulse with high accuracy.

The presently disclosed subject matter has been made in order to solvesuch a problem of the related art, and an object thereof is to provide apulse discrimination device and an electrocardiogram analyzer thatdiscriminate a pacing pulse included in an electrical signal from aliving body with high accuracy.

SUMMARY

A pulse discrimination device relating to a first aspect of thepresently disclosed subject matter is configured to receive electricalsignals from a plurality of positions of a living body to which a pacingdevice for outputting a pacing pulse to cause a heart to beat isattached, and is configured to discriminate the pacing pulse included inthe electrical signals. The pulse discrimination device includes: adifferential processor configured to calculate a difference of theelectrical signals received from the plurality of positions; a sumprocessor configured to calculate a sum of the electrical signalsreceived from the plurality of positions; and a pulse discriminationunit configured to discriminate the pacing pulse included in theelectrical signals based on the difference obtained by the differentialprocessor and the sum obtained by the sum processor.

A pulse discrimination device relating to a second aspect of thepresently disclosed subject matter is configured to receive electricalsignals from a plurality of positions of a living body to which a pacingdevice for outputting a pacing pulse to cause a heart to beat isattached, and is configured to discriminate the pacing pulse included inthe electrical signals. The pulse discrimination device includes: apulse width acquisition unit configured to acquire a pulse width of theelectrical signals received from the plurality of positions based onvariation in an intensity of the electrical signals; and a pulsediscrimination unit configured to discriminate the pacing pulse includedin the electrical signals based on the pulse width acquired by the pulsewidth acquisition unit.

An electrocardiogram analyzer relating to a third aspect of thepresently disclosed subject matter includes: the above-described pulsediscrimination device; an electrocardiogram generator configured togenerate an electrocardiogram based on an electrical signal receivedfrom a living body; and a display configured to display theelectrocardiogram generated by the electrocardiogram generator.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram illustrating a configuration of anelectrocardiogram analyzer including a pulse discrimination devicerelating to Embodiment 1 of the presently disclosed subject matter;

FIG. 2 is a flowchart illustrating an operation of judging a pacingpulse by a pulse discrimination unit;

FIG. 3 is a diagram illustrating a state in which an electrocardiogramis displayed on a display;

FIG. 4 is a block diagram illustrating a main part of a pulsediscrimination device relating to Embodiment 2;

FIG. 5 is a block diagram illustrating a main part of a pulsediscrimination device relating to Embodiment 3;

FIG. 6 is a flowchart illustrating an operation of Embodiment 3;

FIG. 7 is a block diagram illustrating a configuration of anelectrocardiogram analyzer including a pulse discrimination devicerelating to Embodiment 4 of the presently disclosed subject matter.

FIG. 8 is a flowchart illustrating an operation of Embodiment 4;

FIG. 9 is a flowchart illustrating an operation of Embodiment 5;

FIG. 10 is a block diagram illustrating a main part of a pulsediscrimination device relating to Embodiment 6; and

FIG. 11 is a flowchart illustrating an operation of Embodiment 6.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the presently disclosed subject matter willbe described by reference to drawings.

Embodiment 1

FIG. 1 illustrates a configuration of an electrocardiogram analyzer 2can include a pulse discrimination device relating to Embodiment 1 ofthe presently disclosed subject matter. The electrocardiogram analyzer 2is connected to a pair of electrodes 1 a and 1 b. The electrocardiogramanalyzer 2 may be, for example, an electrocardiograph forelectrocardiogram measurement, or may be a patient monitor capable ofacquiring other vital sign parameters (respiration, body temperature,pulse rate, blood pressure, and the like). The patient monitor may be aso-called bedside monitor or a portable device such as a medicaltelemeter. The electrocardiogram analyzer 2 may be configured such thata display 5 can be attached and detached, or configured to transfervarious data used for display.

The electrodes 1 a and 1 b are respectively disposed at two positions onthe living body to which a pacing device is attached, and an electricalsignal from the living body is input thereto. Here, the pacing device isdisposed on the living body and causes a heart to beat by sequentiallyoutputting pacing pulses toward the heart. Therefore, the electricalsignals input into the electrodes 1 a and 1 b include not only a signalindicating movement of the heart, but also a pacing pulse. Theelectrodes 1 a and 1 b are arranged with respect to the pacing devicesuch that the pacing pulses P are input as differential signals, thatis, the pacing pulses P input to the electrode 1 a and the pacing pulsesP input to the electrodes 1 b are input in opposite phases.

Examples of the pacing device include a pacemaker and the like.

The electrocardiogram analyzer 2 can include a pulse discriminationdevice 2 a, an A/D converter 3, an electrocardiogram generator 4, and adisplay 5.

The pulse discrimination device 2 a can include a receiver 6 connectedto the electrodes 1 a and 1 b; a sum processor 7, an amplifier 8 a, ahigh-pass filter 9 a, and an absolute value processor 10 a aresequentially connected to the receiver 6; and a differential processor11, an amplifier 8 b, a high-pass filter 9 b, and an absolute valueprocessor 10 b are sequentially connected to the receiver 6. Theamplifier 8 b is also connected to the A/D converter 3. The absolutevalue processors 10 a and 10 b are respectively connected to acomparison unit 12, and the display 5 is connected to the comparisonunit 12 via the pulse discrimination unit 13. A main body controller 14is connected to the comparison unit 12 and the pulse discrimination unit13.

The receiver 6 receives the electrical signals input to the electrodes 1a and 1 b, and the electrodes 1 a and 1 b are detachably connectedthereto.

The sum processor 7 calculates a sum of the electrical signals receivedby the receiver 6 from the electrodes 1 a and 1 b, and may be configuredwith, for example, a summing amplifier circuit.

The differential processor 11 calculates a difference of the electricalsignals received by the receiver 6 from the electrodes 1 a and 1 b, andmay be configured with, for example, a differential amplifier circuit.

The amplifier 8 a amplifies the intensity of the electrical signalsummed by the sum processor 7. The amplifier 8 b amplifies the intensityof the electrical signal differentiated by the differential processor11. The amplification units 8 a and 8 b may be configured with, forexample, amplifier circuits.

The high-pass filter 9 a attenuates a component lower than apredetermined frequency among the electrical signal amplified by theamplifier 8 a, and extracts a component having a high frequency. Thehigh-pass filter 9 b attenuates a component lower than a predeterminedfrequency among the electrical signal amplified by the amplifier 8 b,and extracts a component having a high frequency.

The absolute value processor 10 a outputs an absolute value of anelectrical signal processed by the high-pass filter 9 a. The absolutevalue processor 10 b outputs an absolute value of an electrical signalprocessed by the high-pass filter 9 b. The absolute value processors 10a and 10 b may be configured with, for example, absolute value circuits.

The comparison unit 12 compares the intensity of the electrical signaloutput from the absolute value processor 10 a with the intensity of theelectrical signal output from the absolute value processor 10 b, and maybe configured with, for example, a comparator circuit.

The pulse discrimination unit 13 discriminates the pacing pulse Pincluded in the electrical signal based on a comparison result of thecomparison unit 12. For example, in a case where the absolute value ofthe difference output from the absolute value processor 10 b is equal toor larger than the absolute value of the sum output from the absolutevalue processor 10 a in the comparison result of the comparison unit 12,the pulse discrimination unit 13 determines the electrical signalsreceived by the receiver 6 are the pacing pulse P. On the other hand, ina case where the absolute value of the difference output from theabsolute value processor 10 b is smaller than the absolute value of thesum output from the absolute value processor 10 a in the comparisonresult of the comparison unit 12, the pulse discrimination unit 13determines the electrical signals received by the receiver 6 are anoise.

The main body controller 14 controls each unit in the pulsediscrimination device 2 a.

The pulse discrimination unit 13 and the main body controller 14 areconfigured with a CPU and an operation program for causing the CPU toperform various processing, but may also be configured with digitalcircuits.

The A/D converter 3 is connected to the amplifier 8 b, and performsanalog/digital conversion on an analog electrical signal amplified bythe amplifier 8 b to generate a digital electrical signal.

The electrocardiogram generator 4 is connected to the A/D converter 3and generates an electrocardiogram based on the digital electricalsignal generated by the A/D converter 3.

The display 5 is connected to the electrocardiogram generator 4 and thepulse discrimination unit 13, displays the electrocardiogram generatedby the electrocardiogram generator 4, and displays a pulse markindicating output of the pacing pulse P at the position in theelectrocardiogram discriminated as the pacing pulse P by the pulsediscrimination unit 13.

Next, operation of Embodiment 1 will be described.

First, the electrodes 1 a and 1 b illustrated in FIG. 1 are arranged attwo positions on the surface of the living body. The pacing device (notillustrated) is attached to the living body, and the pacing pulses P forcausing the heart to beat are sequentially output from the pacing devicetoward the heart. Therefore, an electrical signal including the pacingpulses P is propagated to the living body, and the electrical signal isinput to the electrodes 1 a and 1 b. Here, the electrodes 1 a and 1 bare arranged at positions such that the pacing pulses P are input asdifferential signals. When an electrical signal is respectively input tothe electrodes 1 a and 1 b, the electrical signal is output from theelectrodes 1 a and 1 b to the receiver 6 of the pulse discriminationdevice 2 a.

When the electrical signal output from the electrodes 1 a and 1 b isreceived by the receiver 6, the receiver 6 outputs the electrical signalreceived from the electrodes 1 a and 1 b to the sum processor 7 andoutputs the electrical signal received from the electrodes 1 a and 1 bto the differential processor 11.

When the electrical signal output from the receiver 6 is input to thesum processor 7, the sum processor 7 processes sum processing of theelectrical signal, that is, calculates the sum of the electrical signalreceived at the two different positions. Therefore, the pacing pulses Pinput as differential signals cancels each other due to the sumprocessing, and the intensity thereof becomes a low value, for example,zero. On the other hand, in general, noises input as in-phase signals,for example, noises caused by vibration of an external device, areincreased by each other and become a large value due to the sumprocessing. The electrical signal obtained via the sum processing isoutput from the sum processor 7 to the amplifier 8 a.

The electrical signal subjected to the sum processing by the sumprocessor 7 is amplified by the amplifier 8 a, and the component havinga high frequency is extracted by the high-pass filter 9 a and input tothe absolute value processor 10 a. Then, the electrical signal input tothe absolute value processor 10 a is subjected to absolute valueconversion, and is output from the absolute value processor 10 a to thecomparison unit 12.

On the other hand, when the electrical signal output from the receiver 6is input to the differential processor 11, the differential processor 11processes differential processing of the electrical signal, that is,calculates the difference of the electrical signal received at the twodifferent positions. Therefore, the pacing pulses P input asdifferential signals are increased by each other and become a largevalue due to the differential processing. On the other hand, noisesinput as in-phase signals are canceled by each other and become a smallvalue. The electrical signal obtained via the differential processing isoutput from the differential processor 11 to the amplifier 8 b.

The electrical signal subjected to the differential processing by thedifferential processor 11 is amplified by the amplifier 8 b, and a riseR component and a fall F component are extracted by the high-pass filter9 b and input to the absolute value processor 10 b. Then, the electricalsignal input to the absolute value processor 10 b is subjected toabsolute value conversion, and is output from the absolute valueprocessor 10 b to the comparison unit 12. The electrical signalamplified by the amplifier 8 b is also output from the amplifier 8 b tothe A/D converter 3.

In this way, the electrical signals processed by the absolute valueprocessors 10 a and 10 b are input to the comparison unit 12. Thus, asillustrated in FIG. 2, in step S1, the comparison unit 12 acquires theabsolute value obtained by differentiating the electrical signals andthe absolute value obtained by summing the electrical signals. Thecomparison unit 12 compares the absolute value obtained bydifferentiating the electrical signals and the absolute value obtainedby summing the electrical signals, and outputs the comparison result tothe pulse discrimination unit 13.

When the comparison result of the comparison unit 12 is input to thepulse discrimination unit 13, in step S2, the pulse discrimination unit13 determines whether or not the absolute value of the difference of theelectrical signal is equal to or larger than the absolute value of thesum of the electrical signals.

Here, the pacing pulses P input as differential signals have an absolutevalue of the difference larger than a predetermined value, and have anabsolute value of the sum equal to or smaller than the predeterminedvalue. On the other hand, the noises input as in-phase signals have anabsolute value of the difference equal to or smaller than thepredetermined value, and have an absolute value of the sum larger thanthe predetermined value. That is, in a case where the pacing pulse P isinput, the absolute value of the difference is equal to or larger thanthe absolute value of the sum, and when a noise is input, the absolutevalue of the difference is smaller than the absolute value of the sum.

Therefore, in a case where the absolute value of the difference of theelectrical signals is equal to or larger than the absolute value of thesum of the electrical signals, in step S3, the pulse discrimination unit13 determines that that part is the pacing pulse P. Then, in step S4,the pulse discrimination unit 13 outputs the detected signal of thepacing pulse P to the display 5. Therefore, in a case where the absolutevalue of the difference of the electrical signals is smaller than theabsolute value of the sum of the electrical signals, in step S5, thepulse discrimination unit 13 determines that that part is a noise.

In this manner, the pulse discrimination unit 13 discriminates thepacing pulse P included in the electrical signals based on thedifference of the electrical signals obtained by the differentialprocessor 11 and the sum of the electrical signals obtained by the sumprocessor 7, that is, based on the characteristics of the pacing pulsesP input as differential signals, and thus can discriminates the pacingpulses P with high accuracy.

In this way, when the pulse discrimination unit 13 has discriminated thepacing pulse P, the process returns to step S1, and discrimination ofthe pacing pulse P is repeatedly performed on the sequentially inputelectrical signals.

Here, the electrical signal output from the amplifier 8 b to the A/Dconverter 3 is converted into a digital electrical signal by the A/Dconverter 3 and then output to the electrocardiogram generator 4. Then,the electrocardiogram generator 4 generates an electrocardiogram basedon the electrical signal input from the A/D converter 3, and outputs theelectrocardiogram signal to the display 5.

Thereby, as illustrated in FIG. 3, an electrocardiogram E indicatingbeats of the heart of the living body is displayed on the display 5. Instep S4, the detected signal of the pacing pulse P output from the pulsediscrimination unit 13 is input to the display 5. Therefore, the display5 displays a pulse mark M indicating output of the pacing pulse P fromthe pacing device in a manner superimposing the electrocardiogram E at aposition corresponding to detection of the pacing pulse P.

In this way, by displaying the pulse mark M in a manner superimposingthe electrocardiogram E, for example, the output timing of the pacingpulse P from the pacing device can be easily grasped, and theelectrocardiogram E can be analyzed in detail.

According to the present embodiment, the pulse discrimination unit 13discriminates the pacing pulse P included in the electrical signalsbased on the difference of the electrical signals obtained by thedifferential processor 11 and the sum of the electrical signals obtainedby the sum processor 7, and thus can discriminates the pacing pulses Pwith high accuracy.

Embodiment 2

In Embodiment 1, the comparison unit 12 preferably compares a peak valueof the absolute value obtained by differentiating the electrical signalswith a peak value of the absolute value obtained by summing theelectrical signals.

For example, as illustrated in FIG. 4, in Embodiment 1, a peak hold unit21 may be connected between the absolute value processors 10 a, 10 b andthe comparison unit 12, and a hold controller 22 and a first timer 23may be sequentially connected to the peak hold unit 21.

The peak hold unit 21 can include a sum peak hold unit 24 and adifference peak hold unit 25.

The sum peak hold unit 24 is connected between the absolute valueprocessor 10 a and the comparison unit 12, and holds the peak value ofthe electrical signal output from the absolute value processor 10 a,that is, the peak value of the absolute value with respect to the sumobtained by the sum processor 7, as a sum peak value.

The difference peak hold unit 25 is connected between the absolute valueprocessor 10 b and the comparison unit 12, and holds the peak value ofthe electrical signal output from the absolute value processor 10 b,that is, the peak value of the absolute value with respect to thedifference obtained by the differential processor 11, as a differencepeak value.

The first timer 23 measures a hold time of the sum peak value held bythe sum peak hold unit 24 and the difference peak value held by thedifference peak hold unit 25.

The hold controller 22 controls the sum peak hold unit 24 and thedifference peak hold unit 25 based on the hold time of the first timer23. Specifically, in a case where the hold time of the first timer 23reaches a predetermined pulse time, the hold controller 22 clears thesum peak value of the sum peak hold unit 24 and the difference peakvalue of the difference peak hold unit 25 back to zero, and performscontrol so as to repeatedly hold the sum peak value and the differencepeak value.

Here, the pulse time is preset based on a pulse width W between the riseR and the fall F of the pacing pulse P, and is preferably determined asa value larger than the pulse width W of the pacing pulse P. Forexample, the pulse time may be set to a value that is larger than thepulse width W of the pacing pulse P and smaller than a time interval atwhich the pacing pulse P is output from the pacing device. For example,the pulse time may be set to 8 ms.

Next, operation of Embodiment 2 will be described.

First, the same as or similarly to Embodiment 1, the electrical signalsinput from the electrodes 1 a and 1 b are input to the absolute valueprocessor 10 a via the sum processor 7, the amplifier 8 a, and thehigh-pass filter 9 a, and are input to the absolute value processor 10 bvia the differential processor 11, the amplifier 8 b, and the high-passfilter 9 b.

Then, the electrical signal input to the absolute value processor 10 ais subjected to absolute value conversion by the absolute valueprocessor 10 a, and then input to the sum peak hold unit 24 to hold thesum peak value. The same or similarly, the electrical signal input tothe absolute value processor 10 b is subjected to absolute valueconversion by the absolute value processor 10 b, and then input to thedifference peak hold unit 25 to hold the difference peak value. At thistime, the hold controller 22 starts the first timer 23 to measure thehold time of the sum peak hold unit 24 and the difference peak hold unit25.

Here, for example, in a case where the pacing pulse P, which isdifferential signals, is input from the electrodes 1 a and 1 b, thedifference peak value is held at a value larger than the predeterminedvalue, and the sum peak value is held at a value equal to or smallerthan the predetermined value. On the other hand, in a case where anoise, which is in-phase signals, is input from the electrodes 1 a and 1b, the difference peak value is held at a value equal to or smaller thanthe predetermined value, and the sum peak value is held at a valuelarger than the predetermined value.

In this way, since the sum peak hold unit 24 holds the sum peak value,and the difference peak hold unit 25 holds the difference peak value,the sum peak value and the difference peak value can be easily acquired.

Therefore, in a case where the difference peak value is not held at avalue larger than the predetermined value and the hold time of the firsttimer 23 reaches the predetermined pulse time, the hold controller 22determines that the pacing pulse P is not detected, i.e., the signal isa noise, clears the sum peak value of the sum peak hold unit 24 and thedifference peak value of the difference peak hold unit 25 back to zero,and clears the hold time of the first timer 23 back to zero. Then, thehold controller 22 restarts the first timer 23.

On the other hand, in a case where the difference peak value is held ata value larger than the predetermined value and the sum peak hold unitis held at a value equal to or smaller than the predetermined valuebefore the hold time of the first timer 23 reaches the pulse time, thehold controller 22 outputs the sum peak value of the sum peak hold unit24 and the difference peak value of the difference peak hold unit 25 tothe comparison unit 12.

In this way, since the hold controller 22 repeatedly controls the sumpeak hold unit 24 and the difference peak hold unit 25 based on the holdtime of the first timer 23, it is possible to sequentially acquire thesum peak value and the difference peak value while easily removing anoise.

Subsequently, when the sum peak value of the sum peak hold unit 24 andthe difference peak value of the difference peak hold unit 25 are inputto the comparison unit 12, the comparison unit 12 compares the sum peakvalue with the difference peak value. At this time, the comparison unit12 compares the sum peak value held by the sum peak hold unit 24 withthe difference peak value held by the difference peak hold unit 25, thatis, compares the values with the highest intensity, so that thedifference between the values can be compared with high accuracy.

The comparison unit 12 outputs the comparison result to the pulsediscrimination unit 13, and the pulse discrimination unit 13 determineswhether or not the difference peak value is equal to or larger than thesum peak value from the comparison result. The same as or similarly toEmbodiment 1, in a case where the difference peak value is equal to orlarger than the sum peak value, the pulse discrimination unit 13determines that that part is the pacing pulse P. On the other hand, in acase where the difference peak value is smaller than the sum peak value,the pulse discrimination unit 13 determines that that part is a noise.

According to the present embodiment, since the pulse discrimination unit13 compares the difference peak value held by the difference peak holdunit 25 with the sum peak value held by the sum peak hold unit 24, it ispossible to discriminate the pacing pulse P with high accuracy.

Embodiment 3

In Embodiments 1 and 2, a pulse detector configured to detect anelectrical pulse included in an electrical signal is preferably newlyarranged.

For example, as illustrated in FIG. 5, in Embodiment 1, a pulse detector61 may be newly connected between the high-pass filter 9 b and the pulsediscrimination unit 13. The pulse detector 61 detects an electricalpulse included in an electrical signal input from the high-pass filter 9b based on variation in an intensity of the electrical signal.Specifically, in a case where the variation in the intensity of theelectrical signal exceeds a preset threshold, the pulse detector 61detects the signal as an electrical pulse. Here, the electrical pulse isa generic term for all pulses included in the electrical signal, andincludes pacing pulses and noise pulses. The noise pulse corresponds to,for example, an in-phase noise and a continuous pulse.

Next, operation of Embodiment 3 will be described with reference to theflowchart of FIG. 6.

First, in step S6, pulse detection by the pulse detector 61 is enabled.Subsequently, the same as or similarly to Embodiment 1, electricalsignals from the living body are received by the receiver 6 via theelectrodes 1 a and 1 b, and then input to the comparison unit 12 via thesum processor 7, the amplifier 8 a, the high-pass filter 9 a, and theabsolute value processor 10 a, and are input to the comparison unit 12via the differential processor 11, the amplifier 8 b, the high-passfilter 9 b, and the absolute value processor 10 b. An electrical signalprocessed by the high-pass filter 9 b is also input to the pulsedetector 61.

The pulse detector 61 detects an electrical pulse included in theelectrical signal input from the high-pass filter 9 b based on thevariation in the intensity of the electrical signal. In a case where anelectrical pulse is detected in step S7, the pulse detector 61 outputsthe detected signal of the electrical pulse to the comparison unit 12,and disables the pulse detection in step S8. On the other hand, in acase where no electrical pulse is detected, the pulse detector 61repeats step S7 until an electrical pulse is detected.

In this way, when the electrical signals processed by the absolute valueprocessors 10 a and 10 b and the detected signal of the electrical pulsedetected by the pulse detector 61 are input to the comparison unit 12,the comparison unit 12 compares the absolute values of the differenceand the absolute value of the sum corresponding to the electrical pulsedetected by the pulse detector 61, and outputs the comparison result tothe pulse discrimination unit 13. Subsequently, the pulse discriminationunit 13 determines in step S2 the same as or similarly to Embodiment 1.The pulse discrimination unit 13 proceeds to step S3 to determine thatthe electrical pulse is the pacing pulse P in a case where it isdetermined that the absolute value of the difference is equal to orlarger than the absolute value of the sum, and proceeds to step S5 todetermine that the electrical pulse is a noise in a case where it isdetermined that the absolute value of the difference is smaller than theabsolute value of the sum.

According to the present embodiment, the pulse discrimination unit 13determines whether or not the absolute value of the difference is equalto or larger than the absolute value of the sum with respect to theelectrical pulse detected by the pulse detector 61, and thus candiscriminate the pacing pulse P included in the electrical signals withhigher accuracy.

Embodiment 4

In the above-described Embodiments 1 to 3, the pulse discrimination unit13 discriminates the pacing pulse P included in the electrical signalsbased on the difference obtained by the differential processor 11 andthe sum obtained by the sum processor 7, but may also discriminate basedon the pulse width W of the pacing pulse P.

For example, as illustrated in FIG. 7, the sum processor 7, theamplifier 8 a, the high-pass filter 9 a, the absolute value processor 10a, the absolute value processor 10 b, and the comparison unit 12 inEmbodiment 1 are excluded, and a pulse discrimination unit 31 isdisposed instead of the pulse discrimination unit 13. A pulse detector32 and a pulse width acquisition unit 33 are sequentially connectedbetween the high-pass filter 9 b and the pulse discrimination unit 31, atimer controller 34 and a second timer 35 are sequentially connected tothe pulse width acquisition unit 33, and the main body controller 14 isconnected to the pulse width acquisition unit 33 and the pulsediscrimination unit 31.

The pulse detector 32 detects the rise R and the fall F of theelectrical signals received from the electrodes 1 a and 1 b arranged attwo positions of the living body, and can include a rise detector 36 anda fall detector 37.

The rise detector 36 is connected between the high-pass filter 9 b andthe pulse width acquisition unit 33, receives the electrical signalobtained by extracting the rise R component and the fall F component inthe high-pass filter 9 b, and detects the rise R based on the variationin the intensity of the electrical signal.

The fall detector 37 is connected between the high-pass filter 9 b andthe pulse width acquisition unit 33, receives the electrical signalobtained by extracting the rise R component and the fall F component inthe high-pass filter 9 b, and detects the fall F based on the variationin the intensity of the electrical signal.

The second timer 35 measures a time between a time of the rise Rdetected by the rise detector 36 and a time of the fall F detected bythe fall detector 37.

The timer controller 34 controls the second timer 35 in accordance withdetection of the rise R and the fall F in the pulse detector 32.Specifically, the timer controller 34 start measurement of the secondtimer 35 when one of the rise R and the fall F is detected in the pulsedetector 32, and to stop and clear the measurement of the second timer32 when the other one of the rise R and the fall F is detected in thepulse detector 32. Further, the timer controller 34 stops and clears thesecond timer 35 in a case where a measurement time of the second timer35 reaches a predetermined pulse time after the one of the rise R andthe fall F is detected and before the other one is detected in the pulsedetector 32.

The pulse width acquisition unit 33 acquires the pulse width W betweenone fall F and another fall F based on the time measured by the secondtimer 35.

The same as or similarly to Embodiment 2, the pulse time is preset basedon the pulse width W of the pacing pulse P, and may be determined as,for example, 8 ms, which is a value larger than the pulse width W of thepacing pulse P.

Next, operation of Embodiment 4 will be described with reference to theflowchart of FIG. 8.

First, in step S11, detection of the rise R in the rise detector 36 isenabled, and detection of the fall F in the fall detector 37 is enabled.The same as or similarly to Embodiment 1, the electrical signals fromthe living body are respectively output to the rise detector 36 and thefall detector 37 of the pulse detector 32 via the electrodes 1 a and 1b, the receiver 6, the differential processor 11, the amplifier 8 b, andthe high-pass filter 9 b.

When the electrical signal is input to the rise detector 36, the risedetector 36 detects the rise R of the electrical pulse based on thevariation in the intensity of the electrical signal. The same orsimilarly, when the electrical signal is input to the fall detector 37,the fall detector 37 detects the fall F of the electrical pulse based onthe variation in the intensity of the electrical signal. In a case wherethe rise R is detected in the rise detector 36, the detected signal isoutput to the pulse width acquisition unit 33, and in a case where thefall F is detected in the fall detector 37, the detected signal isoutput to the pulse width acquisition unit 33.

Then, in step S12, the pulse width acquisition unit 33 repeatedlydetermines whether or not one of the rise R and the fall F is detected.Here, for example, in a case where the detected signal is input from therise detector 36 to the pulse width acquisition unit 33, the pulse widthacquisition unit 33 determines that the rise R is detected as one of therise R and the fall F, and disables detection of the rise R by the risedetector 36 in Step S13. In addition, the timer controller 34 starts thesecond timer 35 in step S14.

Subsequently, when the detected signal is input from the fall detector37 to the pulse width acquisition unit 33, the pulse width acquisitionunit 33 determines that the fall F is detected as the other of the riseR and the fall F in step S15, and proceeds to step S16. On the otherhand, in a case where no detected signal is input from the fall detector37 to the pulse width acquisition unit 33, the pulse width acquisitionunit 33 determines that the fall F is not detected, and proceeds to stepS17.

When the process proceeds to step S16, the pulse width acquisition unit33 disables detection of the falling F by the fall detector 37, and instep S18, acquires the measurement time of the second timer 35 when thefalling F is detected, that is, the pulse width W between the rise R andthe fall F, via the timer controller 34.

In this way, the pulse width acquisition unit 33 can easily acquire thepulse width W between the rise R and the fall F only by measuring thedetection times of the rise R and the fall F with the second timer 35via the timer controller 34. The pulse width W thus acquired is outputfrom the pulse width acquisition unit 33 to the pulse discriminationunit 31.

When the pulse width W is input from the pulse width acquisition unit 33to the pulse discrimination unit 31, the pulse discrimination unit 31determines whether or not the pulse width W is within a predeterminedrange in step S19. Here, the predetermined range is preset based on thepulse width W of the pacing pulse P. In general, the pulse width W ofthe pacing pulse P tends to fall within a range of from 0.2 ms to 3 ms,and for example, the predetermined range may be set to from 0.2 ms to 3ms.

In a case where the pulse width W is within the predetermined range, theprocess proceeds to step S20, and the pulse discrimination unit 31determines that the electrical pulse is the pacing pulse P. On the otherhand, in a case where it is determined that the pulse width W is notwithin the predetermined range, the process proceeds to step S23, andthe pulse discrimination unit 31 determines that the electrical pulse isa noise.

In this way, the pulse discrimination unit 31 discriminates the pacingpulse P included in the electrical signals based on the pulse width W,and thus can discriminate the pacing pulses P with high accuracy.

When the pacing pulse P is detected in step S20, the pulsediscrimination unit 31 proceeds to step S21, and outputs the detectedsignal of the pacing pulse P to the display 5. Then, in step S22, thetimer controller 34 stops and clears the second timer 35.

On the other hand, when the process proceeds to step S17, the pulsewidth acquisition unit 33 determines whether or not the measurement timeof the second timer 35 is equal to or larger than the predeterminedpulse time. In a case where the pulse width acquisition unit 33determines that the measurement time of the second timer 35 is equal toor larger than the pulse time, the pulse width acquisition unit 33outputs the determination result to the pulse discrimination unit 31,and in step S23, the pulse discrimination unit 31 determines that theelectrical pulse is a noise. In a case where the measurement time of thesecond timer 35 is smaller than the pulse time, the pulse widthacquisition unit 33 returns to step S15 to repeatedly determine whetheror not the fall F is detected.

In this way, when the pulse discrimination unit 31 determines in stepS23 that the electrical pulse is a noise, the process proceeds to stepS22, and the timer controller 34 stops and clears the second timer 35.

When the timer controller 34 clears the second timer 35, the processreturns to step S11, detection of the rising R and the falling F isenabled again, and the rise R and the fall F are repeatedly detectedwith respect to the sequentially input electrical signals.

According to the present embodiment, the pulse discrimination unit 31discriminates the pacing pulse P included in the electrical signalsbased on the pulse width W, and thus can discriminate the pacing pulsesP with high accuracy.

Embodiment 5

In Embodiment 4, after the pulse discrimination unit 31 determines thatthe electrical pulse included in the electrical signal is the pacingpulse P in step S20, detection of the rise R and the fall F ispreferably stopped until just before the next pacing pulse P is inputfrom the electrodes 1 a and 1 b.

For example, as illustrated in FIG. 9, after the pulse discriminationunit 31 determines in step S20 of Embodiment 4 that the electrical pulseincluded in the electrical signal is the pacing pulse P and the detectedsignal of the pacing pulse P is output to the display 5 in step S21, theprocess proceeds to step S24. The pulse width acquisition unit 33determines whether or not the measurement time of the second timer 35 isequal to or larger than the predetermined pulse time.

Here, the same as or similarly to Embodiment 2, the pulse time is presetbased on a pulse width W of the pacing pulse P, and may be determinedas, for example, 8 ms, which is a value larger than the pulse width W ofthe pacing pulse P, and smaller than the time interval at which thepacing pulse P is output from the pacing device.

When the pulse width acquisition unit 33 determines that the measurementtime of the second timer 35 is equal to or larger than the pulse time,the pulse width acquisition unit 33 proceeds to step S22 to stop andclear the second timer via the timer controller 34. On the other hand,in a case where the pulse width acquisition unit 33 determines that themeasurement time of the second timer 35 is smaller than the pulse time,the pulse width acquisition unit 33 repeats step S24 until themeasurement time of the second timer 35 becomes equal to or larger thanthe pulse time.

In this way, since after the pacing pulse P is detected, detection ofthe rise R and the fall F is stopped until just before the next pacingpulse P is input to the electrodes 1 a and 1 b, it is possible toeliminate a noise input until the next pacing pulse P is detected,thereby preventing detection of a noise.

According to the present embodiment, after it is determined that theelectrical pulse included in the electrical signal is the pacing pulseP, the pulse width acquisition unit 33 stops detection of the rise R andthe fall F until just before the next pacing pulse P is input from theelectrodes 1 a and 1 b, and thus it is possible to prevent detection ofa noise.

Embodiment 6

In the above-described Embodiments 1 to 3, the pacing pulse P isdiscriminated based on the difference and the sum, and in Embodiments 4and 5, the pacing pulse P is discriminated based on the pulse width W.However, the pacing pulse P included in the electrical signal may alsobe discriminated by combining Embodiments 1 to 3 and Embodiments 4 and5.

For example, as illustrated in FIG. 10, a pulse discrimination unit 51is disposed instead of the pulse discrimination unit 13 in Embodiment 2,the pulse detector 32 and the pulse width acquisition unit 33 ofEmbodiment 4 are sequentially connected to the high-pass filter 9 b, andthe pulse width acquisition unit 33 is connected to the pulsediscrimination unit 51. The timer controller 34 and the second timer 35of Embodiment 4 are sequentially connected to the pulse widthacquisition unit 33, and the main body controller 14 is connected to thepulse width acquisition unit 33, the timer controller 34, and the pulsediscrimination unit 51. Further, the pulse width acquisition unit 33 isconnected to the hold controller 22.

The pulse discrimination unit 51 discriminates the pacing pulse Pincluded in the electrical signal based on the pulse width W acquired bythe pulse width acquisition unit 33, and further discriminates thepacing pulse P based on the difference obtained by the differentialprocessor 11 and the sum obtained by the sum processor 7.

Next, operation of Embodiment 6 will be described with reference to theflowchart of FIG. 11.

First, the same as or similarly to Embodiment 4, in step S11, detectionof the rise R in the rise detector 36 is enabled, and detection of thefall F in the fall detector 37 is enabled. In step S31, the holdcontroller 22 starts the first timer 23 to measure the hold time of thesum peak hold unit 24 and the difference peak hold unit 25.

The electrical signals input from the electrodes 1 a and 1 b are inputto the sum peak hold unit 24 via the sum processor 7, the amplifier 8 a,the high-pass filter 9 a, and the absolute value processor 10 a, and areinput to the difference peak hold unit 25 via the differential processor11, the amplifier 8 b, the high-pass filter 9 b, and the absolute valueprocessor 10 b. Thereby, the sum peak hold unit 24 holds the sum peakvalues, and the difference peak hold unit 25 holds the difference peakvalue.

On the other hand, the electrical signal processed by the high-passfilter 9 b is also input to the rise detector 36 and the fall detector37, and in a case where the rise R and the fall F are detected by therise detector 36 and the fall detector 37, the detected signals areinput to the pulse width acquisition unit 33, respectively. Then, instep S12, the pulse width acquisition unit 33 determines whether or notone of the rise R and the fall F is detected.

In a case where the pulse width acquisition unit 33 determines that oneof the rise R and the fall F is detected, the pulse width acquiring unit33 outputs a determination signal to the hold controller 22. Therefore,in a case where one of the rise R and the fall F is not detected, thepulse width acquisition unit 33 does not output a determination signalto the hold controller 22. At this time, in step S32, the holdcontroller 22 determines whether or not the hold time of the first timer23 is equal to or larger than the predetermined pulse time.

The same as or similarly to Embodiment 2, the pulse time is preset basedon the pulse width W of the pacing pulse P, and may be determined as,for example, 8 ms, which is a value larger than the pulse width W of thepacing pulse P.

In a case where the hold controller 22 determines that the hold time ofthe first timer 23 is equal to or larger than the pulse time, the holdcontroller 22 determines that the detected electrical pulse is a noise,proceeds to step S35, and stops and clears the first timer 23. The holdcontroller 22 stops and clears hold of the sum peak value of the sumpeak hold unit 24 and the difference peak value of the difference peakhold unit 25, respectively. On the other hand, in a case where the holdcontroller 22 determines that the hold time of the first timer 23 issmaller than the pulse time, the hold controller 22 returns to step S12to repeatedly determine whether or not one of the rise R and the fall Fis detected by the pulse width acquisition unit 33.

In this way, the hold controller 22 is capable of easily controlling thesum peak hold unit 24 and the difference peak hold unit 25 based on thehold time of the first timer 23, and is capable of easily removing anoise.

In a case where, in step S12, the pulse width acquisition unit 33determines that one of the rise R and the fall F is detected, forexample, determines that the detected signal is input from the risedetector 36 and the rise R is detected, the same as or similarly toEmbodiment 4, the pulse width acquisition unit 33 disables detection ofthe rise R by the rise detector 36 in step S13, and the timer controller34 starts the second timer in step S14.

Subsequently, in step S15, the pulse width acquisition unit 33determines whether or not the falling F is detected, and in a case wherethe falling F is detected, the pulse width acquisition unit 33 outputsthe determination signal to the hold controller 22, and proceeds to stepS16 to disables detection of the falling F by the fall detector 37. Onthe other hand, in a case where the pulse width acquisition unit 33determines that the fall F is not detected, the pulse width acquisitionunit 33 proceeds to step S17 to be processed in the same manner the sameas or similarly to Embodiment 4.

When the pulse width acquisition unit 33 disables detection of the fallF in step S16, the pulse width acquisition unit 33 proceeds to step S18to acquire the measurement time of the second timer 35, that is, thepulse width W, via the timer controller 34. The pulse width acquisitionunit 33 outputs the acquired pulse width W to the pulse discriminationunit 51.

Here, when the determination signal output when the pulse widthacquisition unit 33 determines that the fall F is detected is input tothe hold controller 22, the hold controller 22 determines that theelectrical pulse is detected, and outputs the sum peak value of the sumpeak hold unit 24 and the difference peak value of the difference peakhold unit 25 to the comparison unit 12. Then, the comparison unit 12compares the sum peak value with the difference peak value, and outputsthe comparison result to the pulse discrimination unit 51.

In this way, when the pulse width W and the comparison result of the sumpeak value and the difference peak value are input to the pulsediscrimination unit 51, the pulse discrimination unit 51 determineswhether or not the pulse width W is within a predetermined range in stepS19.

In a case where the pulse discrimination unit 51 determines that thepulse width W is within the predetermined range, the pulsediscrimination unit 51 proceeds to step S33 to determine whether or notthe difference peak value is equal to or larger than the sum peak valuebased on the comparison result input from the comparison unit 12. On theother hand, in a case where the pulse discrimination unit 51 determinesthat the pulse width W falls out of the predetermined range, the pulsediscrimination unit 51 proceeds to step S23 to determine that theelectrical pulse is a noise.

In a case where the pulse discrimination unit 51 determines that thedifference peak value is equal to or larger than the sum peak value instep S33, the pulse discrimination unit 51 proceeds to step S20 todetermine the electrical pulse is the pacing pulse P. On the other hand,in a case where the difference peak value is smaller than the sum peakvalue, the pulse discrimination unit 51 proceeds to step S23 todetermine the electrical pulse is a noise.

In this way, the pulse discrimination unit 51 discriminates based on thecomparison result of the difference peak value and the sum peak value inaddition to the pulse width W, and thus can discriminate the pacingpulses P with high accuracy.

In this way, when the pulse discrimination unit 51 determines that theelectrical pulse is the pacing pulse P in step S20, or as a noise instep S23, the process proceeds to step S34, and the timer controller 34stops and clears the second timer 35. Further, in step S35, the holdcontroller 22 stops and clears the first timer 23.

When the first timer 23 is cleared in step S35, the process returns tostep S11, detection of the rising R and the falling F is enabled again,and the rise R and the fall F are repeatedly detected with respect tothe sequentially input electrical signals.

According to the present embodiment, the pulse discrimination unit 51discriminates based on the comparison result of the difference peakvalue and the sum peak value in addition to the pulse width W, and thuscan discriminates the pacing pulses P included in the electrical signalswith high accuracy.

In the above-described Embodiments 1 to 6, the electrodes 1 a and 1 bare detachably connected to the receiver 6, but are not limited theretoas long as they are electrically connected to the receiver 6. Forexample, the electrodes 1 a and 1 b may be integrally connected orwirelessly connected to the receiver 6.

In the above-described Embodiments 1 to 6, the electrodes 1 a and 1 bare disposed at two positions on the living body, but are not limited totwo as long as they are capable of receiving electrical signals from aplurality of positions of the living body.

A pulse discrimination device relating to a first aspect of thepresently disclosed subject matter is configured to receive electricalsignals from a plurality of positions of a living body to which a pacingdevice for outputting a pacing pulse to cause a heart to beat isattached, and is configured to discriminate the pacing pulse included inthe electrical signals. The pulse discrimination device includes: adifferential processor configured to calculate a difference of theelectrical signals received from the plurality of positions; a sumprocessor configured to calculate a sum of the electrical signalsreceived from the plurality of positions; and a pulse discriminationunit configured to discriminate the pacing pulse included in theelectrical signals based on the difference obtained by the differentialprocessor and the sum obtained by the sum processor.

Here, the pulse discrimination device may further include a peak holdunit configured to hold a peak value of an absolute value with respectto the difference obtained by the differential processor as a differencepeak value, and to hold a peak value of an absolute value with respectto the sum obtained by the sum processor as a sum peak value. The pulsediscrimination unit may be configured to determine that the electricalsignals received from the plurality of positions are the pacing pulse,in a case where the difference peak value held by the peak hold unit isequal to or larger than the sum peak value.

In addition, the pulse discrimination device my further include: a firsttimer configured to measure a hold time of the difference peak value andthe sum peak value which are held by the peak hold unit; and a holdcontroller configured to clear the difference peak value and the sumpeak value of the peak hold unit, in a case where the hold time of thefirst timer reaches a pulse time predetermined based on a time of apulse width of the pacing pulse.

In addition, the pulse time may be set to a value larger than the timeof the pulse width of the pacing pulse.

In addition, the pulse discrimination unit may be configured todetermine that the electrical signals received from the plurality ofpositions are the pacing pulse, in a case where an absolute value of thedifference is equal to or larger than an absolute value of the sum.

In addition, the pulse discrimination device may further include a pulsewidth acquisition unit configured to acquire a pulse width of theelectrical signals received from the plurality of positions based onvariation in an intensity of the electrical signals. The pulsediscrimination unit may be configured to discriminate the pacing pulsefurther based on the pulse width acquired by the pulse width acquisitionunit.

A pulse discrimination device relating to a second aspect of thepresently disclosed subject matter is configured to receive electricalsignals from a plurality of positions of a living body to which a pacingdevice for outputting a pacing pulse to cause a heart to beat isattached, and is configured to discriminate the pacing pulse included inthe electrical signals. The pulse discrimination device includes: apulse width acquisition unit configured to acquire a pulse width of theelectrical signals received from the plurality of positions based onvariation in an intensity of the electrical signals; and a pulsediscrimination unit configured to discriminate the pacing pulse includedin the electrical signals based on the pulse width acquired by the pulsewidth acquisition unit.

Here, the pulse discrimination may further include: a pulse detectorconfigured to detect a rise and a fall of the electrical signalsreceived from the plurality of positions; and a second timer configuredto measure a time between the rise and the fall that are detected by thepulse detector. The pulse width acquisition unit may be configured toacquire the time between the rise and the fall, which is measured by thesecond timer as the pulse width.

In addition, the pulse discrimination device may further include a timercontroller configured to start measurement of the second timer when oneof the rise and the fall is detected by the pulse detector, and to stopand clear the measurement of the second timer when another one of therise and the fall is detected by the pulse detector.

In addition, the timer controller may be configured to determine that anelectrical pulse detected by the pulse detector is a noise, and to stopand clear a measurement time of the second timer, in a case where themeasurement time of the second timer reaches a pulse time after the oneof the rise and the fall is detected and before said another one of therise and the fall is detected, the pulse time being predetermined basedon a pulse width of the pacing pulse.

An electrocardiogram analyzer relating to a third aspect of thepresently disclosed subject matter includes: the above-described pulsediscrimination device; an electrocardiogram generator configured togenerate an electrocardiogram based on an electrical signal receivedfrom a living body; and a display configured to display theelectrocardiogram generated by the electrocardiogram generator.

According to the presently disclosed subject matter, since the pulsediscrimination unit discriminates the pacing pulse included in theelectrical signals based on the difference calculated by thedifferential processor and the sum calculated by the sum processor, itis possible to provide a pulse discrimination device and anelectrocardiogram analyzer that discriminate a pacing pulse included inan electrical signal from a living body with high accuracy.

What is claimed is:
 1. A pulse discrimination device configured toreceive electrical signals from a plurality of positions of a livingbody to which a pacing device for outputting a pacing pulse to cause aheart to beat is attached, and configured to discriminate the pacingpulse included in the electrical signals, the pulse discriminationdevice comprising: a pulse width acquisition unit configured to acquirea pulse width of the electrical signals received from the plurality ofpositions based on variation in an intensity of the electrical signals;and a pulse discrimination unit configured to discriminate the pacingpulse included in the electrical signals based on the pulse widthacquired by the pulse width acquisition unit.
 2. The pulsediscrimination device according to claim 1, further comprising: a pulsedetector configured to detect a rise and a fall of the electricalsignals received from the plurality of positions; and a second timerconfigured to measure a time between the rise and the fall that aredetected by the pulse detector, wherein the pulse width acquisition unitis configured to acquire the time between the rise and the fall, whichis measured by the second timer as the pulse width.
 3. The pulsediscrimination device according to claim 2, further comprising a timercontroller configured to start measurement of the second timer when oneof the rise and the fall is detected by the pulse detector, and to stopand clear the measurement of the second timer when another one of therise and the fall is detected by the pulse detector.
 4. The pulsediscrimination device according to claim 3, wherein the timer controlleris configured to determine that an electrical pulse detected by thepulse detector is a noise, and to stop and clear a measurement time ofthe second timer, in a case where the measurement time of the secondtimer reaches a pulse time after the one of the rise and the fall isdetected and before said another one of the rise and the fall isdetected, the pulse time being predetermined based on a pulse width ofthe pacing pulse.